Geography Reference
In-Depth Information
The point 6 is located 115
,
287
.
428 m East of the
reference
meridian
with the
meridian number
4, that is
L
0
=12
◦
and
5
,
964
,
460
.
428 m
North of the equator
.
Second meridan strip.
x
2
(Gauss
−
Krueger) =
−
82
,
350
.
056 m
,y
2
(Gauss
−
Krueger)
=5
,
963
,
764
.
424 m
.
Easting: 5,417,649.944m, Northing: 5,963,764.424m.
The point 6 is located 82
,
350
.
056 m West of the
reference
meridian
with the
meridian number
5, that is
L
0
=15
◦
and
5
,
963
,
764
.
424 m
North of the equator
(Fig.
15.13
).
End of Example.
If we choose a
Universal Transverse Mercator Projection
as our reference system, we have to
acknowledge that the central meridian is not equidistantly mapped. Instead, two meridians
West
and East of the central meridian
are mapped equidistantly.
We compute the scale factor of the reference meridian by minimizing the
Airy distortion measure
in a given strip with respect to the ellipsoid-of-revolution in a preceding section. There is an
International Agreement to use the scale factor 0.999587.
In practice, we use relative to the
reference meridian
the
zone number
(
L
0
+3
◦
)
/
6
◦
+ 30. In use is also the ref-
erence
Easting/Northing
with respect to the meridians
L
0
=
−
177
◦
= 177
◦
W
,L
0
=
−
171
◦
, ···,L
0
=
−
3
◦
,L
0
=
3
◦
, ..., L
0
= 171
◦
= 171
◦
E. For instance, Germany is
located between the zone 32 and the zone 33. The easterly
coordinate is equipped with an offset number 500,000m,
called “false Easting”. In contrast, Northings are changed
by an offset of 10,000,000m on the southern hemisphere
(
y<
0) to avoid negative coordinates, an artificial effect,
called “false Northing”. The strip overlap is chosen as 0
.
5
◦
.
Example 15.7 (UTM coordinates. Easting versus Northing coordinates).
The point 1 is described relative to the Geodetic Reference System 80 (GRS 80), the surface
normal coordinates by
L
=6
.
8
◦
and
B
=51
.
2
◦
. Compare with Figs.
15.14
,
15.15
,and
15.16
.
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